Mybatis拦截器实现SQL性能监控

　　Mybatis拦截器只能拦截四类对象，分别为：Executor、ParameterHandler、StatementHandler、ResultSetHandler，而SQL数据库的操作都是从Executor开始，因此要记录Mybatis数据库操作的耗时，需要拦截Executor类，代码实现如下：

/**
 * 数据库操作性能拦截器,记录耗时
 * @Intercepts定义Signature数组,因此可以拦截多个,但是只能拦截类型为：
 *         Executor
 *         ParameterHandler
 *         StatementHandler
 *         ResultSetHandler
 * */
@Intercepts(value = { 
        @Signature (type=Executor.class,
                method="update",
                args={MappedStatement.class,Object.class}),
        @Signature(type=Executor.class,
        method="query",
        args={MappedStatement.class,Object.class,RowBounds.class,ResultHandler.class,
                CacheKey.class,BoundSql.class}),
        @Signature(type=Executor.class,
        method="query",
        args={MappedStatement.class,Object.class,RowBounds.class,ResultHandler.class})})
public class TimerInterceptor implements Interceptor {

    private static final Logger logger = Logger.getLogger(TimerInterceptor.class);
    
    /**
     * 实现拦截的地方
     * */
    @Override
    public Object intercept(Invocation invocation) throws Throwable {
        Object target = invocation.getTarget();
        Object result = null;
        if (target instanceof Executor) {
            long start = System.currentTimeMillis();
            Method method = invocation.getMethod();
            /**执行方法*/
            result = invocation.proceed();
            long end = System.currentTimeMillis();
            logger.info("[TimerInterceptor] execute [" + method.getName() + "] cost [" + (end - start) + "] ms");
        }
        return result;
    }

    /**
     * Plugin.wrap生成拦截代理对象
     * */
    @Override
    public Object plugin(Object target) {
        return Plugin.wrap(target, this);
    }

    @Override
    public void setProperties(Properties properties) {

    }

}

　　完成上面的拦截后，需要将该类在Mybatis配置文件中声明，如下：

<plugins>
     <!-- SQL性能拦截器 -->
     <plugin interceptor="com.quar.interceptor.TimerInterceptor" />
</plugins>